A method for controlling transmission powers by a communication apparatus in a wireless communication system supporting a plurality of component carriers. When a sounding reference symbol (SRS) transmission overlaps with a physical uplink shared channel (PUSCH) transmission in a time domain, the communication apparatus checks whether a total of a PUSCH transmission power for the PUSCH transmission on a first component carrier and a SRS transmission power for the SRS transmission on a second component carrier exceeds a maximum transmission power configured for the communication apparatus, and drops the SRS transmission if the total of the PUSCH transmission power and the SRS transmission power exceeds the maximum transmission power configured for the communication apparatus.